There's a big difference between trying it for fun for a few weeks and making a real attempt to switch. I taught my son how to throw righthanded at age three before it became apparent he was lefthanded. At thirteen he started hearing how lefty pitchers got more opportunity to prove themselves as pitchers (like dad). We started working on throwing mechanics. After a couple of weeks he decided there was too much to work on to excel under normal circumstances than to distract it with learning to throw lefthanded. Besides, given where he's at righthanded as a soph, who would be interested in a tall, hard throwing lefty by his senior year anyway? My bad.
I did teach him (and his sister) to hit lefthanded.